substrate specificities of the pentose dehydrogenase and pentonolactonase toward d-ribose and ribonolactone, respectively, and the presence of a highly specific ribonate dehydratase are prerequisites of the oxidative Haloarcula degradation of d-ribose in spp. This is the first characterization of an oxidative degradation pathway of d- ribose to α -ketoglutarate in archaea. Importance: The utilization and degradation of d-ribose in archaea, the third domain of life, have not been Haloarcula analyzed so far. We show that species utilize d- ribose, which is degraded to α -ketoglutarate via a novel oxidative pathway. Evidence is presented that the oxidative degradation of d-ribose involves novel promiscuous enzymes, pentose dehydrogenase and pentonolactonase, and a novel sugar acid dehydratase highly specific for ribonate. This is the first report of an oxidative degradation pathway of d-ribose in archaea, which differs from the canonical nonoxidative pathway of d-ribose degradation reported for most bacteria. The data contribute to our understanding of the unusual sugar degradation pathways and enzymes in archaea.

Kadoya, S., Krissansen-Totton, J., Catling, D.C., 2020. Probable cold and alkaline surface environment of the Hadean Earth caused by impact ejecta weathering. Geochemistry, Geophysics, Geosystems 21, e2019GC008734.

https://doi.org/10.1029/2019GC008734 Abstract: Constraining the surface environment of the early Earth is essential for understanding the origin and p evolution of life. The release of cations from silicate weathering depends on climatic temperature and CO , 2 and such cations sequester into carbonate minerals in or on the seafloor, providing a stabilizing feedback on climate. Previous studies have suggested that this carbonate-silicate cycle can keep the early Earth's surface p temperature moderate by increasing CO to compensate for the faint young Sun. However, the Hadean Earth 2 experienced a high meteorite impactor flux, which produced ejecta that is easily weathered by carbonic acid. In this study, we estimated the histories of surface temperature and ocean pH during the Hadean and early Archean using a new model that includes the weathering of impact ejecta, empirically justified seafloor weathering, and p ocean carbonate chemistry. We find that relatively low CO and surface temperatures are probable during the 2 +3.01 +84.1-14.4 p Hadean, for example, at 4.3 Ga, (in bar) log ( CO ) is 2.21 and temperature is 259.2 [2σ] K. 10 2 -2.54 +1.21-1.69 Such a low would result in a circumneutral to basic pH of seawater, for example, 7.90 [2σ] at 4.3 Ga. A probably cold and alkaline marine environment is associated with a high impact flux. Hence, if there was an interval of an enhanced impact flux, that is, Late Heavy Bombardment, similar conditions may have existed in the early Archean. Therefore, if the origin of life occurred in the Hadean, life likely emerged in a cold global environment and probably spread into an alkaline ocean. Plain Language Summary: The Earth's environment during the Hadean eon, 4.5 to 4 billion years ago, is obscured by a lack of geological evidence. However, life likely arose then, so improving our knowledge of the early environment is essential for understanding the origin and evolution of life. Here, we build a geological carbon cycle model that simulates the early surface environment and generates probability distributions for the level of atmospheric carbon dioxide (CO ), average surface temperature, and ocean pH over time. During the 2 Hadean, CO dissolved in water is consumed by reacting with material ejected from meteorite impacts, so CO 2 2 levels tend to be low and the greenhouse effect weak. The consequences are low surface temperature and alkaline seawater. The probability that the surface temperature was lower than the freezing point of water and that seawater pH exceeded 7 is 70% at 4.3 billion years ago. Thus, if life began in the Hadean, it likely emerged in a cold global environment, and early life may have spread into an alkaline ocean.

Kalinowski, A.A., Gurba, L.W., 2020. Interpretation of vitrinite reflectance - depth profiles in the Northern Denison Trough, Bowen Basin, Australia. International Journal of Coal Geology 219, 103367.

http://www.sciencedirect.com/science/article/pii/S0166516219300576 The Denison Trough, Bowen Basin, Australia, is a mature hydrocarbon province that contains Permian to Triassic coal and gas bearing sediments deposited in deltaic to shallow marine shelf conditions. The sandstone reservoirs of the Permian Aldebaran Sandstone, Freitag Formation and Catherine Sandstone of the Northern Denison Trough (NDT) were evaluated for their CO storage potential as part of the Queensland Government's 2